Similar Length, Similar Weight.
Colt AR15A4 with a KAC M5 RAS and a Trijicon TA31RCO-A4.
M4A1 SOCOM barreled carbine with a KAC M4 RAS, Surefire 762 SOCOM Mini, and a Trijicon TA31RCO-M4.
This is a Colt 6933 (well actually a 6945 lower with a 6933 upper). The factory trigger was replaced with a Geissele SSA trigger. A KAC M4 RAS was added to provide a quad rail and add some weight to the front of the gun. The carry handle was removed and replaced with a Matech rear sight. The TA31F ACOG scope was installed because I tried to sell it but no one wanted a $500 beat up ACOG.
It is not as light and handy as a stock 6933, but it is a fun little setup.
Some years back I decided I would convert one of my AR15s to a short barreled rifle. After paying a 200 dollar tax stamp and waiting a long time, I started with a LMT 10.5 inch upper.
The first time I shot that short upper I decided I wanted a suppressor. That ended up costing me a great deal of money.
That picture shows two products I ended up having issues with. My Eotech 512 had the battery contacts fail on me. I also found out that the threads on my LMT upper were not cut concentric to the bore. That issue lead to a 10 minute of angle point of impact shift between suppressed and unsuppressed.
My first silencer was a Gemtech M4-02. The can performed great but it was a thread on can. Each time I screwed it on or off the rifle I was worried about damaging the threads and I had to keep a flash hider or thread protected around for when I wasn’t using the can. So I did more research on suppressors and I ended up buying a Surefire 556K can.
I found I preferred using ACOG optics on my SBR. The ACOG gave me better target recognition and the bullet drop chart aided in shooting farther distances.
In the above photo my rifle has a Surefire muzzle break. That break stayed on my rifle for one whole range session. I find the increased flash and blast of a muzzle break on a short barreled rifle not worth the minimal amount of reduced recoil.
Around the time I decided I would have to do something about the major point of impact shift with my LMT upper I found out about a new rail on the market, the Daniel Defense MK18RISII. I bought one along with a 10.5 inch medium contour match barrel.
When the above photo was taken I was trying out an early production Magpul UBR. Many people on gun forums were claiming this was the ultimate rifle stock. I found it to be awkward and heavy and very quickly got rid of it. They don’t seem to be that popular any more.
Since then I have had a SBR AR15 in 9mm, 5.45. I also had a LWRC PSD in 5.56. The pistol caliber carbines are fun, but lack the usefulness at longer distances. The LWRC with its 8.5 inch barrel and piston system was heavier then my 10.5 inch direct impingement uppers.
The 10 inch 5.56 SBR is the shortest I prefer to go. Shorter then that you give up a great deal in ballistics and terminal performance. A longer rifle starts to get awkward when using a suppressor.
I really love the short barreled AR15, but it is not something I would recommend to everyone. Unless you are using suppressors I don’t think SBRs are that worth while. If your thinking about getting into a short barreled AR15, look at the Colt 6933 and the Colt 6945. I’ve purchased a Colt 6945 and am eagerly awaiting it.
Over the years, Trijicon has been making incremental changes in the ACOG line of scopes. Here are a few pictures that show a M150 model made in 2013 and a couple year old TA31RCO-M4 model to show some of the newest little changes.
One of the more noticeable external changes is that many of the newer 3.5x and 4x scopes have the bosses that allow for mini-red dot mounting.
The top ACOG has the bosses (ears near the eye piece) to allow for piggyback mini-red dot mounting. The only downside to having the MRD bosses is that you can no longer slip on a flip up lens cap on the eye piece.
A smaller less noticable external change is that newer ACOG’s no longer have a bible verse on the side of them. This was removed after it was made widely known in the public, and we wouldn’t want a bible verse on our military rifles because we don’t want to offend the people we are killing.
Formally the ACOGs had JN8:12 marked on the side after the model type.
Many new ACOG scopes come with 1/2 MOA turret adjustments now instead of the old 1/3 MOA coin slots. While this is a coarser adjustment, the new turrets are much easier to adjust, and increase the water resistances of the optic. I like how some of the newer ACOGs are marked with clear external markings showing which way you need to adjust the turret to move the point of impact.
Trijicon has also changed their reticles. Now more of the reticle is illuminated then before on the many of their ACOG scopes. While Trijicon has changed the amount of illumination in the tritium only TA01 series of ACOGs often, this last change increased the the illuminated area on the TA31 red chevron line of scopes. Previously these had the red chevron and the 300m post illuminated, but now the 400m and 500m lines and much of the bar leading to 600m is illuminated. Trijicon’s reticle pictures on their website have been updated to reflect these changes.
Sometimes you might want to mount an optic to a fixed carry handle AR. There are a few different ways to do so, but I think one of the best is the old A.R.M.S. #02 mount.
There are many knock offs of the A.R.M.S. #02 that are no where near as good quality. Many cheap similar scope mounts that are made in China break when you try to tighten the mounting screw. Now I am not much a fan of ARMS products, but this one does what it is suppose to do. So I keep one around in case I feel the desire to slap an optic on an A1 or A2 upper.
Today I learned of a LaRue product I didn’t know about before. It is conveniently labeled “ARMORER’S TOOL”.
It is simply a piece of plastic holding a LaRue adjustment wrench and a hex key Allen wrench for tightening or loosing LaRue ACOG mounts. A nifty little combo tool for those that use a good many LaRue ACOG mounts.